1. Field of the Invention
The present invention relates to protective housings and to heavy duty industrial plastic electrical connectors including electrical contacts located in composite plastic bodies. More particularly, the invention is directed to reinforced composite plastic housings and to reinforced composite plastic electrical connectors which withstand mechanical abuse and exposures to corrosive chemical environments and to a method for manufacturing such electrical connectors.
2. Description of the Prior Art
Conventional commercially available industrial heavy duty electrical connector units include plugs and receptacles with a metal protective body for the electrical contacts and a plastic electrical insulating section for separation of the electrical contacts. The metal protective body is conveniently given a suitable surface treatment or coating to retard corrosion that is met in use. Industrial heavy duty electrical connectors are used for distribution of electrical power to electrically operated devices such as motors, generator sets, compressors, heating and cooling units, welders, conveyors, lighting systems and similar equipment. These connectors are used indoors and outdoors and in hazardous and non-hazardous areas of, for example, chemical and petrochemical plants, process industry facilities, oil drilling platforms, aerospace facilities, marine locations and the like. Materials used for manufacturing such electrical connectors must be able to withstand environmental and abuse exposures so as to minimize damage to the connector and to maximumze safety in operation after such exposures. The use of a metal protective body in conventional heavy duty electrical connectors has several drawbacks including expensee, excess weight, susceptability of the metal to corrosive attack and the requirement of separate insulating sections because of metal's poor insulating properties.
Plastics have been under investigation as a replacement for metal protective bodies in conventional commercial heavy duty electrical connectors. Plastics are desirable because of their well known resistance to corrodents which attack metals, they have good electrical insulating proerties, they are light weight, and are relatively inexpensive.
The use of plastics, however, in heavy duty electrical connectors has previously met with problems. These problems have arisen due to the notch sensitivity and excessive deformation under load of non-reinforced thermoplastic resins, to the brittle fracture characteristics of both fiber-reinforced plastics and filled thermosetting resin materials and to the reduction of mechanical properties and/or dimensional integrity of most thermoplastic resins on exposure to aggressive chemicals and gases met in hazardous location use.
Production of thermoplastic electrical connectors for light duty use is well-known in the art. U.S. Pat. No. 3,494,998 to Anhalt, for example, discloses a method of connector manufacturing utilizing thermoplastic materials to surround the electrical element and form the body of the connector. Such conventional plastic electrical connectors, however, are not suited for heavy duty use because of their notch sensitivity, excessive deformation under load and their low resistance to aggressive chemical environments.